Production of Poly(β-hydroxybutyrate-co-β- hydroxyvalerate) by Two-stage Fed-batch Fermentation of Alcaligenes eutrophus

Lee, In Young,Kim, Guk jin,Shin, Yong Cheol,Chang, Ho Nam,Park, Young Hoon 한국미생물 · 생명공학회 1995 Journal of microbiology and biotechnology Vol.5 No.5

Production of poly(β-hydroxybutyrate-co-β-hydroxyvalerate)[poly(HB-co-HV)] from glucose and propionic acid was studied in a two-stage fed-batch fermentation using Alcaligenes eutrophus NCIMB 11599. When either glucose became sufficient or the feeding rate of propionic acid decreased, production of poly(HB-co-HV) increased but concomitantly resulted in a reduced fraction of HV. During the copolymer accumulation stage, the specific production rate of hydroxyvalerate (HV) increased up to 0.013 (g-HV/g-RCM/h) but it decreased as propionic acid was accumulated. Control of the propionic acid concentration in the medium, therefore, is considered to be one of the most important operating parameters for production of poly(HB-co-HV) with a higher HV fraction. A high titre of poly(HB-co-HV) (85.6 g/ℓ) with HV fraction of 11.4 ㏖% could be obtained in 50 h by controlling the propionic acid concentration at 1 to 4 g/ℓ.

고내압 MOSFET의 고온 영역에서의 전기적 특성 분석

구용서,Koo, Yong-Seo 한국전기전자학회 2007 전기전자학회논문지 Vol.11 No.3

본 논문에서는 고온 환경에서의 대칭형 HV-MOSFET과 비대칭형 HV-MOSFET 구동 소자들의 채널길이, 확장 드레인 영역의 길이의 변화에 따른 전기적 특성변화를 실험을 통해 분석 하였으며 각각의 구조별로 고온 환경에서 확장 드레인의 길이와 채널 길이의 변화에 따른 전기적 특성을 분석하였다. 실험 결과 비대칭 구조는 400K의 온도에서 드레인 전류가 300K에서 보다 약 25% 이상 감소하였고, 트랜스 컨덕턴스는 약 40% 감소, 온 저항은 약 30% 증가 하는 것을 알 수 있었다. 이러한 변화는 주로 온도 증가에 따른 캐리어 이동도의 감소에 따른 현상으로 사료 된다. 대칭 구조의 경우는 비대칭 구조보다 드레인 전류와 트랜스 컨덕턴스의 변화폭이 적었으며 각각 20%, 35%감소를 보였으며, 온 저항은 확장 드레인영역이 길어져 35%의 더 큰 증가량을 보였다. 주로 고온 환경에서 동작하는 고전압 MOSFET(HV-MOSFET)의 설계 시에는 고온 환경을 고려한 소자의 설계가 요구되며, 각 설계변수의 최적화가 필요하다. In this study, the electrical characteristics of Symmetric and Asymmetric High Voltage MOSFET(HV-MOSFET) under high temperature were investigated. And, the specific on-resistance, threshold voltage, transconductance, drain current of the HV-MOSFETs were measured over a temperatures range of 300K ${\leq}$ T ${\leq}$400K. From the result of measured data, specific on-resistance increases slightly with increasing temperature. Especially, at high temperature(at 400K) specific on-resistance was increased about 30% than that in room temperature. And, in high temperature condition (at 400K), drain current was decreased about 30%, Also, transconductance(gm) was decreases with increasing temperature.

Animal species identification by co-amplification of hypervariableregion 1 (HV1) and cytochrome b in mitochondrial DNA

임시근,박기원 한국분석과학회 2005 분석과학 Vol.18 No.3

Mitochondrial DNA (mt DNA) sequence analysis has been a useful tool for species identification of animals and human individuals. Two hypervariable regions (HV1 and HV2) in control region of mitochondrial genome were analyzed for human individual identification. In case of animal species identification, several genes on mt DNA such as cytochrome b (cytb), RNAs, cytochrome oxidases (CO) were used. In this study, co-amplification of HV1 and cytb was carried out in order to check the contamination of animal DNA and to verify the human DNA. The primer sets used in PCR were H15997/L16236 for HV1 and H14724/L15149 for cytb. PCR products for HV1 and cytb were 239bp and 425bp, respectively. The appearance of two bands on agarose gel implied the DNA came from human, however the single band of cytb gene represented the non-human animal DNA.

n-ARY P-Hv-Groups

M. Ghadiri,B. N. Waphare 한국전산응용수학회 2008 Journal of applied mathematics & informatics Vol.26 No.5

n-ary H_v-structures is a generalisation of both n-ary structures and Hv-structures. A wide class of n-ary Hv-groups is the n-ary P-H_v-groups that is concidered in this paper. In this paper the notion of a normal subgroup of an n-ary P-H_v-group is introduced and the isomorphism theorems for n-ary P-H_v-groups are stated and proved. Also some examples and related properties are investigated.

SiC IGBT degradation mechanism investigation under HV‑H3TRB tests

Ziming Wu,Zongbei Dai,Jian Zhou,Huafeng Dong,Wencan Wang,Feiwan Xie,Haoran Wang,Jiahui Yan,Xiyu Chen,Shaohua Yang,Fugen Wu 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.2

The high voltage-high humidity-high temperature reverse bias (HV-H3TRB) test was utilized to evaluate the reliability of silicon carbide insulated gate bipolar transistors (SiC IGBTs). Moisture invasion often induces termination/passivation and metal corrosion. Therefore, the HV-H3TRB test is generally used to assess termination / passivation robustness. However, under the HV-H3TRB test conditions, gate quality degradation may occur. In this study, the dominant degradation mechanism of SiC IGBTs was investigated. The changes of the most sensitive static characteristics (e.g., threshold voltage, breakdown voltage, and leakage current) were recorded. The threshold voltage decreased and leakage current increased substantially after > 1000 h of HV-H3TRB tests under 85 ℃/85% RH climate conditions. Capacitance-voltage (C-V) curve measurements indicated that the mobile ions at the SiC/SiO2 interface or in the gate oxide likely caused the threshold-voltage instability in the SiC IGBTs after the HV-H3TRB tests. This instability can be recovered by applying a negative gate bias. Subsequent failure analysis confirmed no corrosion of metals or termination/passivation in the device, which indicates the robustness of the passivation (consisting of phosphor-silicate glass and Si3N4). Therefore, the gate quality appears to be a significant reliability risk for SiC IGBTs under high humidity, high temperature, and high voltage conditions.

EBV associated hydroa vacciniforme-like eruption in the patient of NK/T cell lymphoma

( Ji Soo Lim ),( Tae Min Kim ),( Kwang Hyun Cho ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.1

Unlike typical hydroa vacciniforme(HV), Epstein-Barr virus(EBV)-associated HV-like eruption shows more variable clinical manifestations. Some patients were reported that they have progressed to malignant lymphoma or leukemia, which are characterized by T-cell immunophenotype. Here we report the first Korean case of EBV-associated HV-like eruption in the patient of NK/T cell lymphoma. A 32-year-old Korean man presented with a late-adolescent onset recurrent necrotic papulovesicles of the face. The patient was diagnosed as EBV-associated NK/T cell lymphoma at oral cavity. The patient also stated childhood onset mosquito type hypersensitivity. A skin biopsy at face showed EBV-associated HV-like eruption, though UV provocation did not reproduce skin lesion. EBV viral loading was detected but low at peripheral blood level. The patient was treated systemic chemotherapeutic treatment and showed complete response for lymphoma, but facial EBV-associated HV-like eruption still remained ups and downs.

LCD TV HV-BLU 시스템에 대한 Ultra-FRFET의 유효성에 관한 연구

이상택(Sang-Taek Lee),연재을(Jae-Eul Yeon),조규민(Kyu-Min Cho),김희준(Hee-Jun Kim) 대한전기학회 2010 전기학회논문지 Vol.59 No.8

This paper introduces a newly improved Ultra-FRFET that has much better reverse recovery characteristic than that of the typical MOSFET and presents its effectiveness in the HV-BLU system of LCD TVs. The reverse recovery time, Trr of Ultra-FRFET is shorter than 40nsec and the peak value of reverse current, irr is also much smaller compared to the typical MOSFET’s, which are sufficient to prevent the MOSFET’s failures without additional FRDs and diodes in HV-BLU system with a half-bridge resonant inverter topology worked by PWM method. In order to verify the validity, the loss analysis and the implementation results in cases when both the conventional solution using typical MOSFETs with additional FRDs and a new solution using Ultra-FRFETs are applied to a HV-BLU of 40” LCD TV are presented. As a result, the effectiveness of Ultra-FRFET was verified and the results are presented in this paper.

고출력 LED 모듈 역률 개선 방법 연구

노영환,Lho, Young Hwan 한국전기전자학회 2014 전기전자학회논문지 Vol.18 No.3

친환경 및 에너지 효율에 대한 관심이 증대되고 있는 가운데 LED(Light Emitting Diode)는 제어방식이 정 전류구동과 SMPS(Switching Mode Power Supply)방식으로 구동하므로 소형화 및 경량화를 이룰 수 있고 전력 소모가 적으며 효율이 높아 광원 및 조명장치에 활용하는데 유용하다. LED 생산업체는 고출력 LED 모듈의 칩 설계 원천기술의 확보가 필요하고, LED 를 조명으로 적용시키기 위해 전력손실을 줄일 수 있는 고출력 LED 모듈 개발을 위한 구동회로 설계와 역률 개선의 방안 연구가 필요하다. 산업현장에서 교류(AC) 직결 LED 구동소자인 HV9910를 일반적으로 사용하고 있다. 본 논문에서 HV9910에 PFC와 Noise Filter를 추가한 구동회로의 역률 및 효율에 대한 개선방법을 시뮬레이션을 통해 검증하는데 있다. Recently, LED (Light Emitting Diode) becomes to be useful to apply for the lightening sources in electric systems and the lightening equipment since the power is less consumed with high efficiency, and the size and the weight of LED are small and light, respectively. The LED is controlled with constant current and SMPS (Switching Mode Power Supply). It is necessary for the LED manufacturer to secure the fundamental technology of designing LED chip, and to study the methodology to improve the power factor (PF) and to design the operational circuit for the development of LED to reduce the power loss in the application of LED lightening. The direct AC (Alternating Current) LED driving circuit, HV9910, is widely used in the industry field. In this paper, it is to evaluate the improved methodology for the power factor and efficiency through simulations when PFC (Power Factor Correction) and Noise Filter are added to HV9910.

HV-SoP Technology for Maskless Fine-Pitch Bumping Process

손지혜,엄용성,최광성,이학선,배현철,이진호 한국전자통신연구원 2015 ETRI Journal Vol.37 No.3

Recently, we have witnessed the gradual miniaturization of electronic devices. In miniaturized devices, flip-chip bonding has become a necessity over other bonding methods. For the electrical connections in miniaturized devices, fine-pitch solder bumping has been widely studied. In this study, high-volume solder-on-pad (HV-SoP) technology was developed using a novel maskless printing method. For the new SoP process, we used a special material called a solder bump maker (SBM). Using an SBM, which consists of resin and solder powder, uniform bumps can easily be made without a mask. To optimize the height of solder bumps, various conditions such as the mask design, oxygen concentration, and processing method are controlled. In this study, a double printing method, which is a modification of a general single printing method, is suggested. The average, maximum, and minimum obtained heights of solder bumps are 28.3 μm, 31.7 μm, and 26.3 μm, respectively. It is expected that the HV-SoP process will reduce the costs for solder bumping and will be used for electrical interconnections in fine-pitch flip-chip bonding.

HV470강의 짧은 균열 성장에 대한 하한계응력확대계수와 피로한도의 연구

현재용,남기우,김민헌 한국동력기계공학회 2019 동력시스템공학회지 Vol.23 No.5

본 연구는 피로파괴과정의 소성거동을 비선형문제로 취급하여 유도한 Ando 식과 미소균열의 피로한도를 취급한 El Haddad 식에서 유도된 Tange 식을 사용하여, 균열재의 피로한도와 하한계응력확대계수를 구하고, 균열길이 의존성을 평가하였다. 균열재의 피로한도와 하한계응력확대계수는 두 식을 사용하여, 균열길이에 따른 영향을 평가하였다. 응력비에 따르는 피로한도는 수정 굿맨과 피로한도 최대값 일정에서 얻어진 것을 사용하였다. 각 응력비에서 얻어진 균열재의 피로한도는 수정 굿맨과 피로한도 최대값 일정에서 얻어진 피로한도의 차이에도 불구하고, 균열깊이가 성장함에 따라서 균열재의 피로한도는 거의 비슷하게 나타났다. 그러나 0.3mm이하의 짧은 균열 피로한도는 각 응력비의 긴 균열의 하한계응력확대계수에서 벗어나, 0.3 mm 이하의 균열은 진전하지 않는 것으로 판단된다. Ando 식의 피로한도 미소균열식과 El Haddad 식에서 유도한 Tange 식은 기본적인 생각 및 식의 형이 전혀 다름에도 불구하고, 하한계응력확대계수는 거의 일치하였다. 수정 굿맨의 피로한도를 사용한 응력확대계수/하한계응력확대계수의 비는 응력비에 관계없이 각 균열 길이에서 같았으나, 결과적으로 를 사용한 Tange 식과 Ando 식은 피로한도 최대값 일정의 응력비가 증가함에 따라서 응력확대계수/하한계응력확대계수의 비가 작아져, 안정하게 평가되었다.